Navien Error Code E205: Water Flow Sensor Failure

Severity
Warning
Type
digital display
Where to look
front panel
Estimated repair cost: $150 — $350 (parts + labor)
Warning: Your Navien boiler has detected a water flow sensor failure, which could lead to system damage if not addressed.

How to Fix Navien Code E205

  1. Check if your boiler is making any unusual noises, which could indicate air in the system.
  2. Try bleeding the air from the system using the built-in air vent.
  3. If the issue persists, do not attempt to fix it yourself. Contact a professional HVAC technician.

How to Reset Navien Code E205

  1. Turn off the unit using the power button on the front panel.
  2. Turn off the gas supply valve.
  3. Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
  4. Restore power at the breaker, then open the gas valve.
  5. Turn the unit back on. If the error returns, the underlying issue needs repair.

What does E205 mean?

The E205 error on your Navien boiler indicates a malfunction in the water flow sensor. This sensor is responsible for monitoring the water flow rate through your boiler. If it's not working correctly, your boiler may not heat water efficiently, leading to system issues. The most common causes for this error are a faulty sensor or air in the system.

Affected Models

Source Documentation

ManualPageReasonAction
NFB-H Installation & Operation Manual 116 Heating Supply Temp.Sensor Check flow, thermistor connector.
Navien NCB-H Installation & Operation Manual 129 Heating Supply Temp.Sensor Contact technical support at 1-800-519-8794.
Navien NFB-H Installation & Operation Manual 116 Heating Supply Temp.Sensor Check flow, thermistor connector.
Navien NFC-H Installation & Operation Manual 127 Abnormal operation: heating supply thermistor Auto RESET
Navien NHB-H Installation & Operation Manual 119 Heating Supply Temp.Sensor Check flow, thermistor connector.
Navien NPF Installation & Operation Manual 126 Abnormal supply water-temp sensor operation for lower limit This error occurs when the water temperature for supply or return does not operate properly. ● Turn off the furnace, turn it on again and check if the furnace operates properly. ● If the furnace is continuously inoperable, contact Technical Support at 1-800-519-8794.

Replacement Parts

PartOEM NumberEst. Cost
Water Flow Sensor 360-00010-00

Related Codes on Same Models

CodeDescriptionSeverity
E001 Ignition Failure Warning
E003 Abnormal Ignition Warning
E004 False Flame Detection Warning
E012 Flame Loss Warning
E016 Overheating Warning
E030 Exhaust Overheat Sensor Warning
E031 Inlet Thermistor Open/Short Warning
E046 Outlet Thermistor Open/Short Warning
E047 DHW Thermistor Open/Short Warning
E060 Fan Motor Abnormality Warning